Season the chicken pieces with garlic powder, salt, and pepper.
Heat olive oil in a large skillet over medium-high heat. Cook the chicken until browned and cooked through, about 5 to 7 minutes. Remove chicken and set aside.
Cook the tortellini according to package directions. Drain and set aside.
In the same skillet, melt the butter over medium heat. Add minced garlic and cook for 1 minute until fragrant.
Whisk in the flour and cook for 1 minute, stirring constantly.
Gradually whisk in the chicken broth until smooth. Bring the mixture to a simmer, stirring until it thickens slightly.
Reduce heat to low. Stir in the heavy cream, Parmesan cheese, and nutmeg. Continue stirring until the sauce is smooth.
Add the fresh spinach to the sauce and cook until it wilts, about 2 minutes.
Return the cooked chicken and the drained tortellini to the skillet. Toss everything gently to coat evenly in the sauce.
Heat through for 1 to 2 minutes before serving.
Notes
For a richer flavor, use pre-cooked rotisserie chicken instead of raw chicken breasts.
If you prefer a thicker sauce, simmer it for a few extra minutes before adding the cream.
Serve immediately with crusty bread or a side salad.